Gear-calculator.



Nm 889,360. PATBNTED JUNE-2,1908.' H. w. PLLows. GEAR GALQULATUR.

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ma bm/f@ llmmsrunalxvunn. mamma' n r No. 1389.360. PATBNTED 'JUNE 2, 1908. H. W. FELLQWS.

GEAR CALCULATOR. .APPLIUATION- FILED 00T. 11,'1907.

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y No. 889,360.

UNITED sriifans PATENT onirica HUGH w.- rELLows, or CAHUENGA, clitiroinviii.-

GEAR-CALCULATOR.'

` '-lepthfor the tooth. Ordinarily, in construct- .ing a setv of bevel gears, the workman plats out the gears by a sketch or drawing and gets the necessary measurements by scaling the "drawing or by mathematical calculation f the instrument.

therefrom, and the. object of the.l present invention is to provide an instrument whereby 'platting is dispensed 'with and the necessary calculations made by working them out on The device' is of a nature akin to the slide rule and is not a drafting instrument."`

The accompanying drawings illustrate the invention and referring thereto Figure 1 is a plan view4 of the instrument. Fig. 2 is an'erid elevation-of the saine looking toward the short arm. Fig. 3 is a perspective of the .slideban Fig. 4 is a perspective of the 'ointen Fig. 5 is a perspective of the blade ar'. Fig. ,6 is -a plan view showing the dif` ferent settings of the instrunieiitin calculating a s ci of gears respectively 5 and 3 inches diameter and of 10 pitch given as an example lin the specification, to illustrate the operapossible.

tion. Fig. 7 is a plat or diagram of the two bevel gear blanks for the pirpose of aiding in vthe'eirplanation of the example given in the s ecification. It should be understood that' t is view is merely for the puiposeof rendering the' explanation of the operation of the instrument clearer than would otherwise be In the actual use of th'e instrument such platting is entirely eliminated. -The said lat also serves to identify the terms used inconnection with the gear blanks and the anglesv thereof. n

' ,The instrument comprises a long arm 1 and .a short arm 2, the edges of the long arm being preferably beveled as shown. The short arm 2 is provided with al slot 3 and the short arm isprovided With four rows of graduations 4, 5, 6`and 7, each row of giaduations being divided into inches, and the inches of row 4 being divided into eighths, the inches of row *Specification of Letters Patent. Application filed October 11, 1907. Serial No. 397,027.

Patented June 2, 190s.

5 being divided into tenths', the inches of row G being divided intofourteenths, and the l inches of row 7 being divided into twelfths.

The long arm 1 is also provided .with four' rows of graduations 4, 5, 6u and 7a, each row being divided into inches and each inch of tlie'respective rows being subdivided into 'eighths, tenths, fourteenths and twelftlis respectively. The respective inch marks in graduations of rows 4, 5a, 6 and 7a are all in register and v'the first inch of each of said rows starts from alii imaginary line, indicated by dotted line 8 Fig. 1, which is parallel with and in the center of slot 3.' The four rows of.

graduations on the short arm are not in register with each other, but, as shown, the graduations of row .4 commence from a point 9 in the center of slot 3 on imaginary line 8 which intersects with the line of the graduations 4a. The graduations `of row 5 coin-` mence from apointopposite an imaginary point 1() in the center of slot 3 in line with row 5a; the. graduations of row 6 commence from an imaginary point 11 in line with row 6a, and the graduations of row 7 commence from an imaginary point 12 in line with the row 7a. There are thus four imaginary points 9, 10, 11 and 12 along the center of slot 3 which respectively aline with rows 4,

5a, 6"L and 7a.

Slidablyarranged o n the short arm l'is an angle plate 13 which has a stud'14 projecting into the slot 3 for guiding it and which has a stud 15, hereinafter termed the center stud, which stud projects above and below the angle late 13 and is threaded on each end to receive rnurled thumb nuts 16and 17. The nut 17 lserves to clamp Athe angle plate 13 in the desired position on short arm 2, whilethe nut 16 serves to clamp a blade 18', the latter having a transverse slot 19 through which the upper part of the center stud 15 passes. -The blade 18 is formed with parallel edges 20 and 2 1 and in ay be adjusted on the center stud 15 so that either edge 20 or edge .21 intersects the axis of center stud l5. In Fig. 1 the blade is shown adjusted with edge 21 intersecting the axis of vcenter stud 15. Eachedge of the blade 18 is graduated in inches which may be subdivided into eighths, sixteenths, thirtyrseconds, etc., like an ordinary scale, and the graduations on each edge start from the center of slot 19. The angle plate 13 has a straight edge 22 which is always perpendicular to the short arm 2 and theedve 22 is arranged on a line which intersects the axis of center stud 15. The angle plate 13 is graduated in degrees for a quarter of a circle, the graduations commencing with 0 at the center of slot. 3, the 90o .division being exactly at the straight edge 22, 'the said degree graduations being formed on an arc concentric with the center stud 15, and each edge ofthe blade 18 is beveled at 20 and 21 to enable accurate reading of the angular position of the blade on the angle plate 13.

Slidably mounted on the long arm 1 is a slide bar 23, shown in detail in Fig. 3, having twoiundercut lugs 24 and 25 which engage the beveled edges of the arm 1, and the lug 24 having in its upper face a groove 26 with undercut walls, as shown, which slidably rcceive a pointer 27. This construction allows the slide bar 23 and pointer 27 to be shifted bodily longitudinally of the long arm 1 and permits the pointer 27 to be adjusted slidably 1n slide'bar 23 transversely of the long arm 1.

A blade bar 28, shown in detail in Fig. 5, is slotted and slidably mounted on blade 18, the blade bar 28 having a total of four rows of graduations 4P, 5", 6b and 7b. Two rows 4') and 5* are provided on one face as shown in Fig. 1 and two rows 6b and 7" are provided on the other face as shown in Fig. 5. The blade bar 28 is reversible tovbring either of its graduated faces'v uppermost and is also reversible end for end, and may be readily slipped off the end of t-he blade 18 when it is recljuired to reverse it.

ln using the instrument let it be assumed that the-two gear blanks shown in Fig. 7 are to be calculated, pitch being 1U, and gear A having a diameter of five inches and gear B having adiameter of three inches.. The caleulationsy to be determined by the instrument are: first, to determine the ,outside turning angle :c of the gear blank A second, to determine the outside diameter z of the gear blank A; third, to determine the eutting angle 1/ of the gear blank A; fourth, to determine the cone of gear blank A; fifth, to determine the length of face t* of th'e tooth.

The dimensions of the gear blank being calculated, whether it be either the large or small gear, are determined on the long arm 1 of the instrument. -'The graduations on the short arm 2 of the instrument are for setting the center stud 15 in line with the center of the companion gear which is not being .calculated. Thus, as gear A is the one to rst be calculated, and as the pitch diameter of gear B is three inches, theangle plate 13 on arm 2 is adjusted so that its straight edge 22 is an inc-.h and a half from the inner end of row 5, that row being graduated for ten pitch. This setting of the instrument is shown in Fig. 6, and thus the center stud 15 is an inch and a half from'the imaginary point 10. The angle plate 13 is then clamped in position by the lower thumb nut 17. In order to deter- \Fig. 6. After the ou lhas been calculated 111 turning angle -uof the backl mine the outside turning angle it is iirst necessary to find the center angle z of the gear. This is done by adjusting the edge 21 of blade 18 so that it intersects with center stud 15. The blade 18 is then swung around on center stud 15- until its edge 21 intersects, on the row 5a, with the Graduation 2%, as that is'half the diameter obgear blank A. The edge 21 of blade 18 is now on a line corresponding with the line r in Fig. 7, this position of the blade being shown in full lines in Fig. 6. The edge 21 of blade 18 now stands over a graduation on the angle plate 13 which denotes the center angle of the gear A,'that is, the angle z, Fig. 7. The slide bar 28 is now adjusted on the blade 18 so that the graduations 5b, which are those for ten pitch, project over the long arm 1 ofthe instrument and lie nearest the'inner end of the long arm 1 and the slide bar is 'then moved up until its edge, having graduations 5b, exactly intersects with edge 21 of blade .18 and with hne of graduatlons 5 on arm 1. The cross bar having thus been adjusted, the blade is then swung outward until the first graduation 5*', nearest .edge 2], int-ersectswith line of graduations 51. This, it will be seen, will now bring the edge of blade bar 28 slightly beyond tlie "25V mark on row 5a, an the blade bar must then be moved slightly inward on blade 1S until the said first inner graduation on the cross bar intersects with the line of row 5A and with the 2% mark thereon. The blade 18 now has a position corresponding to the line edge 21 of blade 18 indicates on the angle plate 13 the degrees of the turning angle or angle x, Fig. 7,' the blade 1S now standing in .position indicated in right hand dotted lines,

this manner, witi-itheinstrumentstill set in this position, the slide bar 23 and pointer 27 are adjusted onthe long arm so that the end of the pointer' intersects at the point which has just been deter- "110 mined on arm 1, then the blade 18, together' with blade bar 28, is swung back away from the pointer 27 which permits of a clear reading on arm 1 to showthe distance of the pointer 27 from imaginary line 8, which dis- 115 tance 1s measured on row 5?, .and this dise' tance being one-half of the outside turning.

diameter of gear blank A maynientally be multiplied by two to give `the total diameter. To determine the cutting angle y, plate 13 is kept in its set position at the 1imark on arm 2 but the blade 1S is shifted on center stud 15 so that edge 20 of blade 18 intersects with the center stud. The blade 18 is then adjusted so that'its t-ersects with graduationQ." on ro'w 5 and then the blade 18 is swung inward','1`.l e., to the left carefullyuntil -the iirs't graduation of row '5'D of 'the cross bar intersects with the line of row 5".

S, Fig. 7, and the 1x00 tside turning anale a:

the angle edge 20 againin- 125 This, as before, brings the 13C a incides Awith graduation edgeoi crossbar 28 from a circle of which the center stud is the' center. This departure increases, obviously, with decreasing radiia'nd .decreases .with increasing radii. lfhe edge of blade-18 now is on a line corresponding to the linet, Fig. 7, and its 'edge l'2 0' indicates on the angle plate. 1 3 the degree lis at 90 to the center angle.

of the cutting angle y of Fig. 7. Obviously, the angle 'u at'which to turn the back cone of gear blankA-is readily .determined from the center angle z, for the angle of the back cone Thus, by subv'tracting'tlii-i' center angle strom 90 will give.

the' `angle u at which to turn the back cone. The lastl calculation, of' determining the 'lengthi of the face ol the tooth, is made by vreading on the scale of blade 18 the distance of `cross bar 2S from the center stud; then 1 dividing this distance b v three, the distance A ditl'erent readily ca cu nv being in ordinary practice one third of the l distance w. Should the distance i. be of ro V)ort-ion, the saine may be as lated aeifoitliilgly on the scale of .blade 18. After the gear blank A has thus been calculated, vthe gear blank B is calculated inthe saine manner, but starting b v setting angle plate 13 at graduation 23, on arm 2 and makingfthe settings 1'71 8 on the long 7 arm 1 for the. gear blank B, the first of which -rivouldbe to'set the cross bar 28 and blade 1S to intersect with graduation 1 f1 on the long arm 1, thus giving .center angle e, and so on. What lcla'im is: v i A gear calculator comprising two arms forming .a square, an angle plate having an intersect-ion point slidable on one arm, linear radnat-ions on each arm with pitch subfivisions, va blade with an edge extending -acrossnsaid intersection point and angularly laerossthe graduations on the other arm, and

an adjustable cross bar on the blade with ,a pitch graduations.

Leo

2. A gear calculator comprising two arms forming a square, an angle plate having an iiitersection point slidablc. on one arm, a pluralityof rows ot' linear graduations on each arinywith pitch subdivisions, the rows ofgraduations on one arm commencing l'rom a commonlinc which intersects said interv,sec-ion point, the rows oligradiiations on the other arm connncncing respectively from the lilies o f the 'lirst spccilicd rows, a blade with kan etheeexten'ding across said intersection point and angularly across the lirst specified rows, and a cross-bar on the blade. provided with a plurality of sets of pitch gradinitions.4

eil-ig merely the 'departure of the tangential A gear calculator comprising two arms forming -a square, an angle plate having an intersection point slidable on one arm, linear graduations on each arinwith pitch subdivisions, a blade with an edge extending across said intersection point and angularhv across the graduations on the. other arm, and an adjustable. cross bar on the blade with pitch graduations, the blade having linear graduations which con'imence from said intersection point..

4. A gear calculator comprising two arms forming a square, an angle plate having an intersection pointI slidable on one arm, linear graduations on each arm with pitch subdivisions a blade adjustable on` the. angle plate to cause either ol' itseilges to intersect said intersection point, the blade extending aiigularly across the other arm.

5. A gear calculator comprising two arms forming a square,v an fangle plate having an intersection point slidable on one. arm, lineal' graduations on each arm with pitch subdivisions, a blade adjustable on the angle plate to cause either of its edges to intersect said intersection point, the blade. extending angularlv across the other arm, anda blade -bar slidable and reversible on the blade and having a plurality ol sets of pitch graduationso'n each face; v Y

6. A gear calculator comprising two arms forming a square, an angle plate having an intersection point slidable on one arnr, linear graduations on each arm with pitch subdivisions, afblailewitlran edge extending across said'in'tersection point and angulai'ly across the graduations on the other arm, an adjusty able cross bar on the blade with pitch graduivatioiis, and a pointer aihiistab'le late-rally and longitudinally of the latter arm for indicating a determined point on thelatter arm after the blade has been swung away `for clear reading.

7. A Ygear calculator comprising two arms forming a square and one of which is slotted, an angle plate slidable on the slotted arm, a center stud oli the angle plate riding in the. slot, a clam i on the. ccnt-erstud for holding the angle plate in the position set, a blade having a transverse slot engaging with the center stud and permitting either edge ol the blade to intersect the stud, and linear graduations on each arm with pitch subdivisions.

8. A gear calculator comprising two arms lorming a square and one ot which is slotted, an angle plate slidable on the slotted arm,a center stud on the angle plate riding in the slot., a clam on the center stud for holding the angle plate in the position set, a blade having a transverse slot engaging with the een ter studiahd permitting either edge of the blade to intersect the stud, linear graduations on each arm with pitch subdivisions, the blade having linear graduations commencing at the eenterof its transverse slot, and al blade bar slidable and reversible on the blade andhaving pifch lgraduations on both faces.

9. A gear dalculator comprising two arms form'in a sqare and oneof which is slotted, an ang e plate s lidable on'the slotted arm, a center stud ontlre angle plate ridin iii-the slot; 'a vclam on the center stud for" olding ther angle p ate in the position set,A a blade having a transverse slot en aging .with the center stud and permitting elther edge of the blade to` intersect the stud7 linear graduation's on each arm With pitch subdivisions7 ,the blade having lineal'v graduations commencing at the center of its transverse slot, a blade bar slidable and reversible'on the blade and having pi h graduations onboth faces,

a slide bar adjustable longitudinall on the unslotted arm, and a pointerslidab e on the cross bar extending over the latter arm.-

10. A gear calculator comprising two arms forming a square and onel of which is slotted, an angle plate slidable'on the slotted arm, a

center stud on the/1 angle. plate riding inthe e slot, a clamp on the center stud for holding -angle plate having a straight edge intersectingwith the center stud and having degree graduations starting from a point over the center of the slot ofthe arm.

In testimony whereof,v Ihave hereunto set my hand at LosAngeles, California, this 4th l da)T of October, 1907 v HUGH W. FELLOWS.

In presence of l GEORGE T. HACKLEY, FRANK L. A. GRAHAM. 

